DSL

example.re

// @broerjuang https://discordapp.com/channels/735469928378925156/736199426309226536/767813964285214812
// parser -> Parser Generator || Parser Combinator
open ReludeParse.Parser;

let input = "
filterBy Category = \"'fantasy'\"
orderBy Rating desc
skip 5
take 10
";

module Operator = {
  type t =
    | Add
    | Substract
    | Multiply
    | Divide
    | Equals
    | LesserThan
    | LesserThanEquals
    | BiggerThan
    | BiggerThanEquals
    | And
    | Or;

  let parseEquals = str("=") |> map(_ => Equals);

  let parser = parseEquals;
};

module Expression = {
  type t =
    | Int(int)
    | Str(string)
    | Identifier(string)
    | Binary(t, Operator.t, t);

  let parseIdentifier =
    manyUntil(str("=") <|> str(" "), anyChar) <#> Relude.List.String.join;

  let parseStrLiteral =
    str("'") *> manyUntil(str("'"), anyChar) <#> Relude.List.String.join;

  let parser = parseStrLiteral <|> parseIdentifier;

  let make = (left, op, right) => {
    switch (op) {
    | Operator.Equals => Binary(left, Operator.Equals, right)
    | _ => Binary(left, Add, right)
    };
  };
};

let x: Expression.t =
  Binary(Identifier("Category"), Equals, Str("fantasy"));

Js.log(
  Expression.make
  <$> ws
  *> (Expression.parser |> map(x => Expression.Identifier(x)))
  <*> Operator.parser
  <*> ws
  *> (Expression.parser |> map(x => Expression.Str(x)))
  |> runParser("         Category ='fantasy'"),
);